1 files changed, 53 insertions, 0 deletions
diff --git a/lib/System/Atomic.cpp b/lib/System/Atomic.cpp
new file mode 100644
index 000000000000..cefd0bbf5538
--- /dev/null
+++ b/lib/System/Atomic.cpp
@@ -0,0 +1,53 @@
+//===-- Atomic.cpp - Atomic Operations --------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This header file implements atomic operations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/System/Atomic.h"
+#include "llvm/Config/config.h"
+
+using namespace llvm;
+
+#if defined(_MSC_VER)
+#include <windows.h>
+#undef MemoryFence
+#endif
+
+void sys::MemoryFence() {
+#if LLVM_MULTITHREADED==0
+  return;
+#else
+#  if defined(__GNUC__)
+  __sync_synchronize();
+#  elif defined(_MSC_VER)
+  MemoryBarrier();
+#  else
+# error No memory fence implementation for your platform!
+#  endif
+#endif
+}
+
+sys::cas_flag sys::CompareAndSwap(volatile sys::cas_flag* ptr,
+                                  sys::cas_flag new_value,
+                                  sys::cas_flag old_value) {
+#if LLVM_MULTITHREADED==0
+  sys::cas_flag result = *ptr;
+  if (result == old_value)
+    *ptr = new_value;
+  return result;
+#elif defined(__GNUC__)
+  return __sync_val_compare_and_swap(ptr, old_value, new_value);
+#elif defined(_MSC_VER)
+  return InterlockedCompareExchange(ptr, new_value, old_value);
+#else
+#  error No compare-and-swap implementation for your platform!
+#endif
+}
+\ No newline at end of file